The apparent attack is the latest in a series of escalating cross border strikes by Moscow and Kyiv targeting energy and military facilities, almost three years after the Kremlin launched its invasion of Ukraine.

"Ukrainian defence forces hit Russian oil depot in Engels" in the Saratov region, the Ukrainian general staff said in a statement on social media.

"It should be noted that this oil depot provided fuel to the Engels-2 military airfield, where enemy strategic aviation is based," the general staff added.

Russian officials acknowledged in earlier statements that Ukraine had attacked the region with unmanned aerial vehicles.

The defence ministry said its air defence systems had downed 32 Ukrainian drones overnight, including 11 over the Saratov region.

The governor of the region, Roman Busargin, said that an emergency response team had been dispatched to an indistrial facility where a fire had broken out after a Ukrainian drone attack, without elaborating on the type of facility hit.

Busargin said that no one had been wounded in the attack.

Kyiv has claimed that its previous attacks on oil facilities were part of ongoing efforts to dent Russian energy revenues that are used to fund the military in Ukraine.

"The destruction of the oil depot creates serious logistical problems for the strategic aviation of the Russian occupants and significantly reduces their ability to strike at peaceful Ukrainian cities and civilian objects," the general staff said this time around.

Kyiv, meanwhile, said overnight that Ukrainian air defence systems had downed 41 Russian drones over the country while another 22 were downed by electronic jamming systems or were lost by air force radars.

Separately, in the southern Ukrainian region of Kherson, which the Kremlin claims is part of Russia, authorities said two people had been killed and five more were wounded by Russian artillery and attack drones.